Here are the latest numbers on solar generation in Ohio, based on data available from the Public Utility Commission of Ohio (PUC)). Each month PUCO releases a list of approved renewable energy generating facilities (available here).
This first chart shows that as of the end of March 2013, there were 1,316 approved solar PV generation facilities located in Ohio with a net installed capacity of 103.8 megawatts.
Both the number of installations and total capacity continue to grow in Ohio. But the news is not all rosy. A different look at the number of installations approved per month shows the pace of approvals is dropping off:
Another interesting data point is that the the solar energy is deployed widely across the state. The following map shows the counties in Ohio with approved solar PV facilities. The darker the county, the more solar energy capacity is installed. It's easy to see where the very large installations at Campbell's Soup plant in Napoleon and AEP/PSEG's Wyandot facility (one of the early large installations) are located. But the striking thing about this map is that every county in the state but one has solar energy.